iptables sample

set_iptables.sh

#!/bin/bash

LAN=eth0

LOCALNET_MASK=`ifconfig $LAN|sed -e 's/^.*Mask:\([^ ]*\)$/\1/p' -e d`

LOCALNET_ADDR=`netstat -rn|grep $LAN|grep $LOCALNET_MASK|cut -f1 -d' '`
LOCALNET=$LOCALNET_ADDR/$LOCALNET_MASK

#/etc/init.d/iptables stop

iptables -P INPUT   DROP
iptables -P OUTPUT  ACCEPT
iptables -P FORWARD DROP

iptables -A INPUT -i lo -j ACCEPT

iptables -A INPUT -s $LOCALNET -j ACCEPT

iptables -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT

sysctl -w net.ipv4.tcp_syncookies=1 > /dev/null
sed -i '/net.ipv4.tcp_syncookies/d' /etc/sysctl.conf
echo "net.ipv4.tcp_syncookies=1" >> /etc/sysctl.conf

sysctl -w net.ipv4.icmp_echo_ignore_broadcasts=1 > /dev/null
sed -i '/net.ipv4.icmp_echo_ignore_broadcasts/d' /etc/sysctl.conf
echo "net.ipv4.icmp_echo_ignore_broadcasts=1" >> /etc/sysctl.conf

sed -i '/net.ipv4.conf.*.accept_redirects/d' /etc/sysctl.conf
for dev in `ls /proc/sys/net/ipv4/conf/`
do
    sysctl -w net.ipv4.conf.$dev.accept_redirects=0 > /dev/null
    echo "net.ipv4.conf.$dev.accept_redirects=0" >> /etc/sysctl.conf
done

sed -i '/net.ipv4.conf.*.accept_source_route/d' /etc/sysctl.conf
for dev in `ls /proc/sys/net/ipv4/conf/`
do
    sysctl -w net.ipv4.conf.$dev.accept_source_route=0 > /dev/null
    echo "net.ipv4.conf.$dev.accept_source_route=0" >> /etc/sysctl.conf
done


iptables -A INPUT -f -j LOG --log-prefix '[IPTABLES FRAGMENT] : '
iptables -A INPUT -f -j DROP

iptables -A INPUT ! -s $LOCALNET -p tcp -m multiport --dports 135,137,138,139,445 -j DROP
iptables -A INPUT ! -s $LOCALNET -p udp -m multiport --dports 135,137,138,139,445 -j DROP
iptables -A OUTPUT ! -d $LOCALNET -p tcp -m multiport --sports 135,137,138,139,445 -j DROP
iptables -A OUTPUT ! -d $LOCALNET -p udp -m multiport --sports 135,137,138,139,445 -j DROP

iptables -N LOG_PINGDEATH
iptables -A LOG_PINGDEATH -m limit --limit 1/s --limit-burst 4 -j ACCEPT
iptables -A LOG_PINGDEATH -j LOG --log-prefix '[IPTABLES PINGDEATH] : '
iptables -A LOG_PINGDEATH -j DROP
iptables -A INPUT -p icmp --icmp-type echo-request -j LOG_PINGDEATH

iptables -A INPUT -d 255.255.255.255 -j DROP
iptables -A INPUT -d 224.0.0.1 -j DROP

iptables -A INPUT -p tcp --dport 113 -j REJECT --reject-with tcp-reset
iptables -A INPUT -p tcp --dport 22 -j ACCEPT
iptables -A INPUT -p tcp --dport 80 -j ACCEPT
iptables -A INPUT -p tcp --dport 443 -j ACCEPT

/etc/init.d/iptables save
/etc/init.d/iptables start